She posted a photo on Instagram of herself walking along a rural path with the girls, who were wearing identical blue and white dresses and one wearing a hat.

"I am deeply grateful to all those in Malawi who helped make this possible, and I ask the media please to respect our privacy during this transitional time," the singer said in her post.

No details were given on the twins' names, age and background.

Madonna adopted Malawian children David Banda and Mercy James in 2006 and 2009. She has two other children, Lourdes and Rocco, from previous relationships.

She established the non-profit Raising Malawi in 2006 to provide health and education programs, particularly for girls.

Madonna sits with her adopted Malawian child Mercy James during a bricklaying ceremony at the site of her Raising Malawi Girls Academy, near the capital Lilongwe, Malawi, April 6, 2010.Mike Hutchings / Reuters